In recent years, there have been medical image processing apparatuses that resolve the conditions of chronic obstructive pulmonary disease (COPD), emphysema, tracheal and bronchial diseases and the like. For example, a medical image processing apparatus matches the positions (matching) of a plurality of images containing tree structures and acquired in different phases of the bronchial three-dimensional (3D) images. However, there are some physiological and pathological differences among 3D images, and variations are present between 3D images in different phases due to motions such as respiration. This leads to difficulty in realizing automatic position matching between 3D images and problems, such as sensitivity to noise, a large amount of computation and so on.
According to Patent Literature 1 (U.S. Pat. No. 7,646,903), tree-like structures representative of physical objects or models are acquired, a path is extracted from a tree-like structure, a path is extracted from another tree-like structure, the two paths are compared to each other by calculating the similarity measurement results, and it is determined whether the paths match up based on the similarity measurement results.
According to Patent Literature 2 (U.S. Laid-open Patent Publication No. 2012/0263364), the matching algorithm is based on association diagram method, and the computation time is significantly reduced by introducing hierarchic separation as well as matching only two sub-trees at once.
However, the disadvantage of the technology described in Patent Literature 1 is in sensitivity to noise and incorrect central line and in that there are too many feature points and too much computation load.
The disadvantage of the technology described in Patent Literature 2 is in that the primary branch points are sensitive to noise and incorrect central line and solving the association diagram is a difficulty in NP solution and there is too much computation load.
Exemplary position matching results according to the prior art will be described. FIG. 12 is a diagram showing exemplary position matching results according to the prior art. When position matching using an image acquired in a phase (hereinafter, referred to as Phase 1) as a base image is performed, the actual position matching results in an image acquired in another phase (hereinafter, Phase 2) for the path of the user's interest marked with “2” (the left diagram in FIG. 12) in the image acquired in Phase 1 are the path marked with “2” (the center diagram in FIG. 12). The position matching results desired for Phase 2 are, as shown in the right diagram in FIG. 12, the path marked with “3”. As described above, it can be seen that the path marked with “2” that is the actual matching results in the image acquired in Phase 2 significantly shifts to the left.